1. Field of the Invention
This invention relates to a double wall beverage container or mug having a wide base, and, in particular, to a double wall beverage mug for containing hot or cold beverages without substantial spillage and wherein the base portion of the beverage mug is substantially wider than the mouth portion of the beverage mug.
2. Background of the Invention and Related Art
Double wall beverage containers for maintaining cold liquids cold and hot liquids hot have long been known in the art. Examples of such beverage containers include U.S. Pat. No. 2,895,636 to MARTIN; U.S. Pat. No. 3,861,565 to RICKMEIER; U.S. Pat. No. 4,151,923 to BERNARDI; U.S. Pat. No. 4,595,437 to YAMIMOTO; U.S. Pat. No. 4,618,066 to VAIL; and British Patent No. 582,294 to WHEELER. U.S. Pat. No. 3,684,123 to BRIDGES, which is hereby incorporated by reference, as though set forth in full herein, discloses a double wall beverage mug. None of these documents, however, discloses a double wall beverage mug for containing hot or cold beverages without substantial spillage and having a base portion substantially wider than the mouth portion of the mug.
British Patent No. 582,294 to WHEELER discloses a container, for the transport and storage of liquids, such as milk in bulk, wherein the container has spaced inner and outer walls to retard heat transfer of the materials stored therein. The container requires the use of a plurality of struts, webs or ribs arranged in the form of a spider so as to provide means whereby the inner and outer walls are mutually supported. Additionally, the outer wall of the container base is formed in a relatively complicated process wherein a lower cylindrical portion of the outer wall is deformed at elevated temperature by a crimping operation so as to produce a series of tapering corrugations, and is progressively turned over inwardly so that the corrugated part becomes a closure for the bottom end of the outer portion, the corrugations assuming a radial disposition and leaving a small central hole which must be plugged with a cementing composition.
ROSS, U.S. Pat. No. 5,217,141, discloses a drinking mug and lid. In one embodiment, the drinking mug has a base which is substantially wider than a neck portion of the mug. In this embodiment, the mug is of a solid wall construction employing only a single wall. In other embodiments, the mug is of a double wall construction; however, in these embodiments, the inner and outer walls are generally right cylindrical.
Mugs wherein the base portion is substantially wider than the mouth portion thereof have generally been constructed of a single wall design. Where a double wall construction is employed for a mug having a wide base portion, the inner wall is generally substantially cylindrical. This has been so because conventional wisdom dictates that the most efficient way to manufacture such a mug is by means wherein the inner liner is generally cylindrical. This is particularly important when processes such as injection molding are employed because liners having a wide base would be difficult, if not impossible, to remove from a mold part in which they were formed. Thus, wide base mugs which result from attempts to provide a wide base mug with double wall construction suffer from a lack of capacity to contain a substantial volume of beverage, at least in part because the inner wall of the mug does not follow the contour of the outer wall of the mug. The volume capacity that would result from usefully employing the entire volume defined by the overall shape of the outer wall of the mug is not realized. Thus, conventional wisdom has dictated that mugs having a double wall construction and a wide base must either have a volume capacity limited to the generally cylindrical shape of the liner or inner wall, and such mugs having a wide base do not utilize the "dead" space between the inner and outer walls of the mug at the base thereof.
The foregoing approaches have failed to provide a double wall insulated beverage container having a substantially wide bottom portion which is capable of containing beverages and retarding transfer of heat to or from such beverages while providing a relatively high-volume beverage capacity also while having a low center of gravity, increased stability and a resistance to tipping of the mug, while substantially inhibiting spillage of the beverage, and there has been a continuing need for improvement.